It said the findings ran 'contrary to claims made by industry and government in the popular press', and that the sector was 'substantially increasing loadings of toxins' to the river, which is linked to high incidences of embryonic mortality and deformity in fish.

The study says the provincial government's own industry-funded monitoring scheme, the Regional Aquatic Monitoring Programme (RAMP), was 'incompetent' and did not make its data available for public or scientific scrutiny.

'We’ve repeatedly questioned RAMP’s findings and nothing has been done,' said the study's co-author, David Schindler of the University of Alberta, who added that ecologists had deliberately set out to test the claims being made by industry and Alberta politicians that all contaminants in the river were from natural sources.

'Given the large amounts of pollutants released, any monitoring programme that cannot detect increases in the environment must be considered as incompetent,' he added.

Although small natural seeps of bitumen into the river do occur, Schindler said the results from this study show them to be no more than a small part of the river pollution.

'Rather than pollutants increasing continuously downstream in the river due to natural sources, as government has claimed, concentrations of the majority of toxins were always highest near sites of industrial activity,' Schindler said. Government deny pollution

Despite the findings, Alberta government officials continue to deny a link between tar sands production and river pollution. A statement on oil sands on the Alberta Environment website states: 'Water quality has been monitored since the early 1970s. Testing has consistently shown there has been no increase in concentrations of contaminants as oil sands development has progressed.'

Schindler said the pollutant levels discovered were a clear violation of the Fisheries Act and that the government could no longer avoid the issue.

'Canada does have weaker regulations, but then we have the Fisheries Act, which absolutely forbids the discharge of "deleterious substances" to or near fish-bearing water. Clearly, this provision is being violated, but it is not being enforced.'

'A robust monitoring program to measure exposure and health of fish, wildlife and humans should be implemented in the region affected by oil sands development,' he concluded.

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